1992 Mazda Protege Emission failing

I have a 1992 Mazda protege 1.8L Manual Transmission. First Emission test HC Cruise limit 170 pass at 98, Idle limit 220 pass at 198. CO Cruise Limit 1.2 pass at 0.33, Idle limit 1.2 failed at 1.79.
After I replace spark plus (found one cracked when I took it out), replace Rotor and Distributors. I did not replace Wires, they are fairly new-3 years and in great condition.
But second test result got worse:
HC Cruise limit 170 pass at 31 --much better, Idle limit 220 failed at 223.
CO Cruise Limit 1.2 pass at 0.09 --much better, Idle limit 1.2 failed at 2.53.
Both idle condition are much worse. I drive (at 9am) to the test center about 5 miles from my home after I replace the parts a night before.
What do you think the problem is and can I be able to fix it myself or get a teachnician to fix it?
Thank you very much for your help.